Automatic Information System (AIS) is an internationally required safety system for all boats larger than 300 tons. However; many smaller ships and recreational boats are using AIS. The system operates under the "See and be Seen" marine safety principle. The system integrates GPS navigation with Marine VHF radio, to broadcast very accurate information to other ships reasonably within 30 miles. Where ships are close to shore, AIS Ground Stations can receive the data messages as well, allowing Harbor Masters, Marinas, Law Enforcement to accurately track shipping. Boating enthusiasts track ships as well in their neighborhood, and more recently, they send their contacts to tracking services via the internet making marine tracking available to anyone globally. MarineTraffic.com is the most popular and displayed on this Website. With over 1400 participating Ground Stations world wide, MarineTraffic.com is displaying over 40,000 vessels at any time.

The diagram depicts two ships in AIS connectivity and a Ground Station monitoring both.

Below is example of AIS tracking of the Ship "Kashi Arrow" northbound for Baltimore. The AIS Ground Station reporting this track is Station 1210 at Deltaville Va. Small triangles behind the ship are Fixes where 1210 has received an AIS message and reported to the internet. This reporting from over 1400 ground stations globally is maintained on a Server in Germany and is managed by the Engineering Dept of the University of the Aegean in Greece under a grant from the International Maritime Association. http://www.MarineTraffic.com makes this available to anyone with internet connectivity.